(someone) can tell (clause)

When you "can tell" something, it means that you know it based on something you saw:

I can tell that you're lying to me.

Could you tell I wanted to leave?

You can leave "that" out in casual conversation, but in formal speaking or in writing you should definitely include it:

I can definitely tell that you're improving.

Use "___ can tell ___" to talk about things that someone noticed out on their own. Don't use if for things that someone heard from other people. In that situation use a phrase like "I heard ___":

I heard you and Desmond weren't getting along.

(someone) has had work done

The phrase "___ has had work done" means that a person has gotten cosmetic surgery. Cosmetic surgery is a kind of surgery that a person gets to make themself look better. Some examples of cosmetic surgery include:

• a face lift (reducing wrinkles in the face by pulling the skin tighter
• liposuction (getting fat removed)
• a "boob job" (breast enlargement)

You can gossip about someone's cosmetic surgery by saying that they've "had work done" or just "had work":

Do you think she's had work done?

Look at his face. He's definitely had work.

This phrase is a little rude, though, so you usually wouldn't use it when talking directly to the person who got cosmetic surgery.